Yikes, my buddy once called some fossils just old rocks... bad move.

Isn't that making it sound way more dangerous than it is? Seems like one of those shop rules that gets passed around more as a scary story than a real daily hazard. People have been working with foundries and hot metal for ages without overthinking a handful of sand. Sure, getting burned is bad, but calling it a "steam burst" makes it sound like a bomb going off. Probably just a good way to get guys to be careful so they don't make a wet mess and ruin the pour.

How old is your forge lining? That stuff can break down and cause weird heat pockets over time. Did this just start happening or has it been getting worse?